US1637237A - Transformer for electric-arc cutting and welding apparatus - Google Patents

Description

July 25, 1927. 7, 37

F. C. OWEN TRANSFORMER FOR ELECTRIC ARC CUTTING AND WELDING APPARATUS Filed April 15,- 1926 6 H w Y Patented July 26, 1927.

* UNITED STATE' S 1,631,237 PATENTQOFF'ICE.

j I FREDERICK CARLISLE OWEN, 0F FAYETTEVILLE, NORTH'GAROLINA.

TRANSFORMER FOR ELECTRIC-ARC CUTTING AND WELDING A PBARATUS.

Application filed Apri1 15, 1926, Serial No. 102,235.

, This invention relates to alternating current electric are cutting and welding apparatus, and more particularly to a novel transformer therefor.

The invent-ion has for one of its objects the provision of a transformer which shall be admitted to permit an are which is uniform and will not burn the work to be easily maintained and which will efiiciently function without the aid of damping devices, rheostats, resistances and the like.

" A further and important object of the invention is the provision of a transformer of the character stated wherein the induced voltage per turn of the secondary winding 1 shall be greater than the impressed voltage f I per turn of the primary winding, whereby -=toreduce to the minimum the current re ,-quired for the efiicient welding of any metal with either a coated, covered or bare electrode.

WVith the foregoing and other objects in view, the nature of which will appear as the description proceeds, the invention consists of the combination and arrangement of parts hereinafter fully described and claimed, and illustrated in the accompanying drawing, wherein: p

Figure 1 is a diagrammatic view of an arc weld ng apparatus embodying the transformer, and

' Figures 2, 3 and 4 are similar views of,

slightly modified forms of the transformer. Corresponding and like parts are referred to in the following description, and designated in the several views of the accompanying drawing, by similar reference char acters. The transformer comprises a laminated core 1 which is preferably though not necessarily of rectangular formation. The core 1. provides but a single metallic magnetic path, and in practice is preferably supported in a vertical position.

The primary circuit or winding of the transformer comprises connected coils 2, 3, 4 and 5 arranged on three adjacent legs of the core 1. The coils 2 and 3 are preferably mounted on the bottom leg and the coils 4 and 5 on the side legs of the core 1. The coils 2 and 3 are reversely arranged. Leads 6 and 7 extending from any suitable source of current supply 'ajre connected to the terminals of the primary winding.

The secondary circuit of the transformer comprises a main or voltage regulating coil 8 mounted on the bottom leg of the core 1,

and an auxiliary or current regulating coil 9 mounted on thetop leg of the core 1. The. coils 8 and 9 are reversely wound or reversely connected, so that thevoltages are added when connected in series by a wire 10. The coil 9 has a greater number of turns or convolutions than the coil 8, and extending from certain turns or convolutions thereof are tap leads 11, any one of which may be connected to the electrode 12 by a lead 13. Thecoil 8 is to be connected to the work 14 by a lead 15.

Current flowing through the primary winding causes a magnetic flux to circulate through the four legs of the core 1. The back voltage in this winding is held down to the minimum due to the fact that this winding embodies a reversely arranged coil.

The back voltage in the reversely arranged coil is in opposition to the corresponding voltage in the remainder. of the coil, and causes a leakage of the flux for the bottom leg of the coral at the ends of this coil. This flux leakage is particularly noticeable at the lower lefthand corner of the core 1. This results in the lowering of the efiective back voltage in the primary winding and a consequent higher exciting current and greater flux density in .the core. In other words, the effect of the reversed coil of the primary winding is a greater induced voltage per turn in the secondary winding than the impressed voltage per turn in the primary winding. It, will thus be apparent that the efficient welding of any metal with either a coated, covered or bare electrode is'possible with the use of but a comparatively small amount of current.

Practically all the flux developed by the primary winding -will thread the main or voltage regulating coil 8, because of the close association of this secondary coil with the primary, and flux in this part of the generated by the primary winding. Owing to the location of the coils, this secondary flux is confined substantially to the to leg of the core 1. The primary flux threa s the bottom and side legs of'the core, and also tends to permeate the top leg. In' this top leg, however, it is opposed and choked back by the flux due to the' secondary Winding 9, and as the result there will be a certain amount of flux leakage from each end of the .primary coils 4 and 5. Owing to tl1eoppos ing and choking effect of the secondary coil 9, however, a very exaggerated leakage takes place at the two upper corners ofthe core. or,- in other words, far the greatest pro: portion offiux i-sforced out of the closed netallicpath into the air at these points,

The larger the current drawn from the secondary winding, the greater this leakage becomes.

As the' result of such leakage, the heavy secondary flux causes the coil 9 to develop high inductance, and act as an impedance coil, so that the phase of the voltage in this art of the secondary winding is shifted. he resulting voltage at the-arc is'therefore reduced, or at least prevented from increasing as the'current increases. The impedanceaction increases with the load, so-

that even on short circuit serves to prevent an excessive or dangerous flow of current. Thus a stable arc is maintained.

, In the modified form of the invention shownin Figure 2, the coils" 2 and t are reversely arran ed as are also the coils 3 and 5, and a third lead 16,extending from a soiirce of current supply, is connected to the remote terminals of the coils 2 and 3. In this form of. the invention, the entire primary winding, or only one-half thereof consisting of either the coils 2 and 4 or the coils 3 and 5 may be employed. In Figure 3, the coils 2, 3, 4 and 5 are connected in parallel;.. that is the coils 2 and 4 and the coils 3 and 5 are paralleled. This form of the invention is especially adapted for heavy welding and cutting. In the form, of the invention shown in Figure 4, the primary winding consists of but two coils 2" and 4.

reverselyarranged. It is to be understood that I am not to berestricted to the'arrangement of the secondary coils on the top and bottom legs of the core, as suchcoils maybe as shouldbe apparent arranged on any two of the-legs."

What is claimed is:-- 1. A transformer having a rectangular core providing. but; a single metallic. magnetic path, a primary winding distributed around three adjacent legsof the core and having 'a re'versedpcoil, and a secondary comprising two sections, one secwindin tion'being wound on'the middle one of said core providing but a single metalliemag-I netic path, a primary winding including a reversed coil and'distributed around three adjacent legs of the core, and a-secondary winding comprising two coils mounted on different legs of the core.

3. A transformer comprising a. core providing but a single magnetic path, a primary winding embodying reversely arranged coils mounted on adjacent legs of the core, asecondary coil mounted on one of said legs of f the core,-and a second secondary coil mounted on another leg of the core and connected to said first secondary coil.

4. A transformer comprising a core, a primary winding distributed about the major portion of .the core and having a reversed coil, a secondary coil on the minor I portion of the core, and a second secondar coil connected to said first secondary c011 core.

5. A transformer -comprisin a core, a primary winding distributed a out a portion of the core and embodying reversely arranged coils, a secondary c'oil onrsaid por tion of the core, and a, second secondary coil on another portion of the core and connected to said first secondary coil.

6. A transformer having a rectangular core, aprimary winding embodying coilson the bottom leg of the core and a 0011 on each side leg of the'core, the coils being connected, one of the coils on the bottom leg and the coil on one of the side legs being reversely arranged and the other coil on the bottom leg and the coil on the other side leg being reversely arranged, a secondary coil on one of said legs, and a second secondary coil on the fourth legof the core and connected to said first secondary coil.

7. A transformer havin a rectangular core, a primary winding emiodying coils on the bottom leg of the core and a'coil on each side leg' of the core, the coils being connected, one of the coils on the bottom leg [and the coil on one ofthe side legs being one, of said legs of the core, and a second secondary coil on the remaining leg of the core and connected to said first secondary coil.

In testimony whereof I aflix my si ature. FREDERICK CARLISLE 0 EN..-

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